In a broad range of fields such as crime prevention systems, disaster prevention systems, on-site supervision systems and medical services, remote monitoring systems for observing the state of affairs from a place different from the site regardless of whether it is at a long distance or short distance are used. In a remote monitoring system, a large number of surveillance cameras are controlled via a network and incoming images are selectively displayed to the user, thus enabling efficient observation. In many cases, surveillance cameras can be controlled in terms of pan angle, tilt angle and zoom magnification, and the user can acquire desired videos. In this case, the user often uses a method of directly controlling the pan angle, tilt angle and zoom magnification while viewing images from surveillance cameras. In such direction control on the surveillance cameras, videos may be delayed because of a delay in the operations of the surveillance cameras or a delay on the network, thus posing the problem that it is difficult to direct surveillance cameras toward the place to be observed.
Moreover, the remote monitoring system as described above has the problem that it is hard to learn which way the user is looking. This is conspicuous in the case where the number of surveillance cameras is increased and where the user can control the pan angle, tilt angle and zoom magnification of the surveillance cameras. Although there is a method of displaying the positions and directions of surveillance cameras on a two-dimensional drawing, the actual site is a three-dimensional space and therefore hard to depict as two-dimensional. Unless the observer is an experienced and skilled person, it is difficult to image from where to where at the site is observed.
PTL 1 is a method for controlling a surveillance camera for remote monitoring. PTL 1 discloses a method using a sensing device such as a sensor. This method utilizes a three-dimensional virtual space. A three-dimensional virtual space model of the site is prepared in advance, and the positions of sensing devices, and the positions, lines of sight and angle-of-view areas of surveillance cameras are three-dimensionally displayed in real time in the three-dimensional space, thus showing where the area whose image is currently being picked up is located.